As can be seen in the Fourth Industrial Revolution, investment in intangible assets is becoming increasingly important. Against the backdrop of this corporate environment, we examined how overconfident CEOs invest in intangible assets and tangible assets. We measured CEOs’ overconfidence through the manager's narrative in 10-K, and identified using textual analysis. The results of this study are as follows. First, as CEOs' optimism increases, investment in tangible and intangible assets increases. Second, overconfident CEOs reduce investment in intangible assets. Third, under the constraints of cash flow, overconfidence CEOs partially increase intangible investment. Fourth, increased intangible investment under cash flow constraints has a positive relationship with long-term performance of firm. This study has the following implications. Since most investments in intangible assets are not accounted for as assets on the balance sheet and are treated as expenses, overconfident managers seem to reduce this. In addition, long-term performance was found to be good if overconfident managers invested in intangible assets even under cash flow constraints. It is interpreted that this is because the intangible assets invested in spite of cash flow constraints act as a core competency for companies.